Updating incrementally is useful, but only if you keep in perspective how little you know and how unreliable your information is based on a single trial. If you forget that, then you end up like the guy who says "Well, I drove drunk once, and I didn't crash my car, so therefore driving drunk isn't dangerous". Sometimes "I don't know" is a better first approximation then anything else.

Of course, it would be accurate to say that we can get some information from this. I mentioned "anything from 10% to 90%", but on the other hand, I would say that the our experience so far makes the hypothesis "99% intelligent species blow themselves up within 50 years of creating a nuclear bomb" pretty unlikely.

However, any hypothesis from "10% of the time, MAD works at preventing a nuclear war" to "99% of the time, MAD works at preventing a nuclear war" or anything in between seems like it's still quite plausible. Based on a sample size of 1, I would say that any hypothesis that fits the observed data at least 10% of the time would have to be considered a plausible hypothesis.